Let-back mechanism for looms



March 3, 1931. J. ROBELLARD 1,794,420,

LET-BACK MECHANISM FOR LOOMS Filed July 13, 1929 Fig. 1.

lnvenfor. doseph Robe I lard Patented Mar. 3, i 1931 UNITEDISTATES PATENT ser es I Josnrn noBELLAfan, onnnw YORK ints, new YORK, ASSIGNOR T DRAPER conronn'rron, 0F nornnnnniivrAssncnnsnrrs, A coaronarron or MAINE inn-linen .iylncnmxsivrron Looms {Application filed ul 13, 1929. Serial'No'. 378,069.

" -.,Thiscinvention has to, s euth roll take- .up mechanism for looms and particularly to the mechanism for'controlling the let-back of the .takeaip mechanism. When the take-n p mechanism is positively driveme means-usu ally including :a p aw-l and ratchetmechan-ism, is employed particularly for limiting the *let- "back of the -take-up mechanismandthenefore of the cloth when the drive is released. I But when the take-up is to he turned back by hand,

. or when the cloth roll is to be unwound, it is necessary to render this mechanism for 0011i trolling and limiting the let-back inactive.

The principal object of the present invention is toprovide means for automatically rendering this mechanism actlvc when the drive of the take-up mechanism is renewed." 1 In a const-ruction commonly employed for controlling and limiting let-back, there -is;:a

-'th-is pawl to active position when the take-hp is started, thus preventing the proper funcjtioning-ofthe takea p mechanism. The more particular ebg eat of the present invention is to provide ,a simple and eflective means for antematically restoringithis pawl to active position when "the drive oi the takeqip mechanism is resumed. 1? l r a These and other objects and features of the invention will appear more fully from the accompanying description and" drawings and .will be partici-ila-rly pointed out in the claims.

The drawings illustrate so muchof p'os-i .tively driven cloth roll takeup mechanism }of a generally familiar type ases necessary tola disclosure of a preferred term of the present invention. 7

Fig. l is a front elevation-oi the left-hand portion of a-loom with a preferred form of thepresent invention embodied therein.

Fig. 2is a detail chiefly inside elevatien looking toward the left of a portion of the mechanism shown in Fig. l. I

As the general construction and operation of a cloth roll takeup mechanism tor looms of the type illustrated is Wellknownandtainil-ia-rto those skilled in the art, it will only be necessary to describe in detail those parts immediately concerned with a preferred embodiment of the present invention.

1' .Alpor tion' of the left-hand side "frame 1, alower girder 2, ;a bracket 3 secured to the loom frame, an intermediate vertical strut member 4:, and a bracket 5 secured to the strut 4 all may bee-f the usual type. The usual take-up roll-and the cloth roll driven therefrom are not shown. llhe'take-up roll is driven from a pinion 6 through a train or gearing -7 of the usual type. The pinion -6 '5 and at theotherend in a long bearing 10 forming part of the bracket 3. The shaitQ,

when the 100m is running, is continuously and positively driven by any suitable means such as the positively driven shaft Hex-tending transversely thereto and connected"therewith by awormand worm wheel'drive.

1 A suitableclutch member 12'is keyed to'the sh aft 9 andoperated by the lever 13 to clutch the pinion 6 an'dratchetwheel 8 to the shaft.

WVhenever the'le-ver 13 is moved to unol'utohing pos1t1on,;as under the control of the weft replenishing mechanism, or =otherwrse,- letback takesplacedue to the tension o'f the cloth and theainountof this let-back must he 'controlled. For that purpose there is commonly provided alet-back or'detent pawl-cooperating with the ratchet wheel 8. This pawl 14 is shown as secured to a shaft 15 piv- 'oted in apawl carrier shown-as bell crank .lever journalled on the shaft9, the longer army of the lever 16 carrying the shaft, 15 and 'the'shorter armheing extended forward "and formed into a weight-17. Thus the action of gravity tends to keep the let-back pawl 14 in engagement with the ratchet wheel 8. During actuation of the take-up the pawl 14 rides idly over the teeth of the ratchet wheel 8, but when let-back takes place and the ratchet wheel 8 rotates in reverse direction, the pawl 14: is held by the ratchet wheel and the pawl carrier swings rearward or clockwise. The forward position of the let-back pawl 1% is determined by a stud 18 projecting from the pawl carrier 16 riding in an arcuate slot 19 in a portion of the bracket 5 by engagement of the stud with a cotter pin 20 adjustably positioned in the bracket. When let-back takes place, as when the clutch "12 is disconnected, the amount of let-back is determined by the distance from this cotter pin 20 to the rear end of the arcuate slot 19.

All of the foregoing construction is well known and familiar and for a more detailed illustration and description thereof reference may be had to the patent to La Ohapelle, No. 1,647,234, November 1, 1927.

When let-back has'taken place, it will be seen that the driving train of gearing 6 and 7 extending to the'take-up roll is locked against reverse rotation by the let-back pawl 14. It is frequently desirable to render the let-back limiting means inactive by the release of the let-back pawl so as toenable the take-up roll to be reversely rotated and particularly to enable the cloth to be unwound. In order to do this, the operator swings the let-back pawl. 14 about its fulcrum 15 over backward and leaves it in an idle or inactive position, while manipulating the take-up and cloth roll. Bi1t when the drive of the take-up mechanism is resumed, the let-back pawl is frequently left lnthis inactive positlon and when the loom runs under these c1rcumstances a defect in the weave occurs. In the present invention means are provided-for automatically restoring the let-back pawl to active position when the loom starts or the drive of the take-up mechanism is resumed.

Asa simple and preferredmeans for securing this result the shaft 9 is provided with a circumferential series of raidialprojections' l acireumferential series of radial projections which conveniently take the form of the teeth 21 of a second ratchet wheel 22 secured to the shaft 9. A holding pawl 23 is pivoted to the let-back pawl 14 as by being pivotally mounted at 24 in an arm 25 secured to the shaft 15 of the letback pawl and this holding pawl: is

of such length that under normal conditions it hangs down in front of theratchet wheel 22. hen it is desired to render the let-back pawl inoperative, theoperator takes hold of the holdingpawl 23 and raises it until the lower end is seated on one ofthe teeth or projections 21, thus holding the let-back pawl 14 V elevated and out of cooperation with the ratchet wheel 8, as shown in Fig.2. i I

When now the drive is resumed and th shaft 9-rota-tes, the tooth or projection upon which the holding pawl 23 is seated moves with the shaft, allowing the holding pawl to drop and the let-back pawl 14: to swing into cooperation with the ratchet wheel 8. Thus it is impossible for the let-back pawl 14 to remain out of cooperation with the ratchet wheel 8 when the loom is running or the shaft 9 is rotating. The let-back pawl is automatically rendered active upon the operation of the loom.

There is thus provided a simple and effective means manually operated to render the let-back limiting means inactive and automatically operated upon operation of the take-up drive to render this let-back limiting der the let-back limiting means active.

2. In a positively driven cloth roll take-up mechanism for looms, a let-back pawl and ratchet mechanism acting to limit let-back to a predetermined amount when the drive is released, means manually movable into a position to render the let-back pawl inactive, and meansacting upon the operation of the take up mechanism to remove said manual means from the said position and to render the let back pawl active. 7

3. In a cloth roll take-up mechanism for looms, a shaft, means for rotating the shaft, a ratchet wheel journalled on the shaft and driving connections therefrom for the take up, means for clutching the ratchet wheel to the shaft, a. pawl carrier journalled on the shaft, a let-back pawl pivoted to the carrier and cooperating with r the ratchet wheel, means for limiting the movement of the pawl carrier-and thereby the amount of let-back upon reverse rotation of the ratchet wheel,

on the shaft, and a holding pawl pivoted to acting whenits free end isseated on one of said projections to hold the let-back pawl out of cooperation with the ratchet wheel and thusxpermit any desired degree of let-back, the said holding pawl being swung out of engagement with the said projection by the rotation of'the shaft/when effecting take-up thus to insure return ofthe let-back pawl to cooperation with the ratchet wheel.

4. A'loom comprising a cloth roll take-up mechanism, actuating means therefor including a driven shaft, two ratchet wheels on the shaft, a let-backpawl cooperating with one ratchet wheel to determine the amount of letback, and a holding pawl manually movable into engagement With the other ratchet Wheel to hold the let-hack pawl out of cooperation with the first ratchet Wheel and thus permit any desired degree of let-back and automatically moved out of engagement with the second ratchet Wheel by the rotation of the shaft thus to insure cooperation on"? the 1et-back pawl With the first ratchet Wheel upon actua- 7 tion of the take-up mechanism.

In testimony whereof, have signed my name to this'sp'ecifieation.

JOSEPH ROBELLARD. 

